Time-dependent density functional theory study on optical properties of GaN doped with alkaline-earth atom

The absorption and the emission spectra of GaN and (Ga,AE)N (AE = Be, Mg, Ca) were calculated by using TDDFT method with cluster model. The calculation results show that Ga₂₆N₂₆H₅₀ cluster only has very weak absorption but has some emission bands in visible region. The band-to-band emission appears around 3.56 eV. If alkaline-earth atoms (Be, Mg and Ca) are doped into GaN, the blue emission band around 3.0 eV appears. Thereinto, Ga₂₅Ca₁N₂₆H₅₀ cluster shows a weaker yellow emission band and a stronger blue one (2.92 eV), which make (Ga,Ca)N material a promising candidate to emit blue light.